1. Field of the Invention
The invention relates to an illumination system, a projection device, and an illumination method.
2. Description of Related Art
In recent years, as the technology of solid-state light source elements becomes mature and the demand for miniaturization of projection devices rises, more and more solid-state light sources have been used as core elements of illumination systems in the projection devices. The solid-state light source has advantages, such as smaller size, longer lifetime, lower power consumption, and high reliability, and is therefore gradually replacing a conventional incandescent light source.
Light emitting diode (LED) and laser are commonly seen solid-state light sources. When designing the illumination system of the projection device, the space that the solid-state light source occupies in the device has to be taken into consideration no matter a light emitting diode light source or a laser light source is used.
Taiwan Patent No. 380213 has disclosed an illumination device that includes a light source, a wedge-shaped glass column matrix, a polarization converter, and a light valve. U.S. Pat. No. 7,445,340 has disclosed an illumination device which includes a light emitting diode light source, a back plate, a light collecting element, a light tube, a focusing optical element, a polarized light splitting element, a reflective filter film, a polarization converter, another focusing optical element, another light tube, a fluorescent material, a reflector, and another back plate. U.S. Pat. No. 6,710,921 has disclosed a polarizing device to generate a polarized light.